The insecticidal and repellent activities of fruit extracts of Xylopia aethiopica (Dunal) A. Rich. and Dennettia tripetala (Baker f.) G.E. Schatz belonging to the family Annonaceae was studied against Sitophilus oryzae (L.), an economic, primary post-harvest pest of rice, and other cereal products. Infested rice grains (100 g) treated with 1, 2, 3, 4, and 5% (w/w) powders of both plants were evaluated for toxicity against S. oryzae every 24 h for 3 d, and during F1 progeny emergence. The essential oils of both plants were also applied at 0.5, 1, 1.5 and 2 mg cm -2 filter paper in Petri dishes for toxicity bioassays at 24 h exposure. Repellence bioassay with 10 μL solution of essential oils on filter paper was performed in a Y-Tube airflow olfactometer. Results indicate that powders of both plants significantly (P < 0.001) caused adult weevil mortality and a reduction in F1 progeny emergence than the control. Essential oils were also significantly (P < 0.001) adulticidal to S. oryzae after 24 h with the highest dose (2 mg cm -2 ) producing 100% mortality respectively. Similarly, both male and female weevils significantly avoided the test arm compared to the control arm in the Y-Tube olfactometer repellence tests. These results suggest that X. aethiopica and D. tripetala natural extracts have potential for use as part of integrated pest management of stored product protection against S. oryzae.

Utilization of plant extracts in pest management is a cheap, environmentally friendly alternative to chemical pesticides. This study was designed to investigate the effects of aqueous extracts of Piper guineensis, Allium sativum and Myristica fragrans on field insect pest damage to leaves of cowpea, prior to flowering. Ife brown cowpea seeds were cultivated on beds assigned to four treatment groups (including a control), in a completely randomized design. 200g/litre of each plant material was used to prepare the stock solution. Field application of extracts was done in the evenings, thrice a week for two months, and data on leaf parameters was collected monthly. Analysis of variance revealed significant differences between the treatment groups at 5% probability level. Only Piper guineensis treated cowpea plants had significantly higher total number of leaves and total leaf area than the control, as well as significantly lower number of damaged leaves, percentage leaf damage, and damaged leaf area, in both months. Piper guineensis was more effective in controlling insect pest damage to leaves of cowpea than Allium sativum and Myristica fragrans.

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Most plant powders possess insecticidal properties and can be used to control insect pests on stored products. This study was conducted to evaluate insecticidal properties of Solanum melongena, Parkia biglobosa. Ipomoea batatas, Colocasia esculenta, Tridax procumbens and Terminalia catappa against Acanthoscelides obtectus Say, an insect pest of stored Phaseolus vulgaris L. The leaves powder of these plants were assessed for aduticidal and reproduction inhibition potential as well as effect on seed weight in a completely randomized design at three treatment concentrations of 0.5%, 1.0%, 1.5% and 0 as the control. All the test plants investigated exhibited insecticidal activity against A. obtectus. Results showed a trend of variation in adult A. JEAI, 36(4): 1-12, 2019; Article no.JEAI.49045 2 obtectus mortality according to post-treatment days and plants powder concentrations. Results analysis revealed that at 14 days after treatment, T. catappa at 1.5% had the highest significant (P=0.05) mortality of 40.21±0.71 i . This was followed by S. melongena which had a similar effect of 39.41± 0.52 i at the same concentration (1.5%). The least significant mortality was observed in the control. At 0.5% T. procumbens, 0.5% Parkia biglobosa, 1.0% I. batatas and 1.0% C. esculenta, leaves powder had comparable effects. It was observed that the control had the highest number of progeny emergence of 181.33 ± 0.88 g after six weeks while T. catappa significantly (P=0.05) inhibited progeny at 1.5% followed by 1.5% S. melongena and 1.5% C. esculenta. Seeds of P. vulgaris treated with 1.5% T. catappa also had the least significant weight loss of 0.93 ± 0.17 g compared to the control which had the highest significant weight loss of 55.68 ± 0.79 g. Though all the plants studied caused significant increase in adult A. obtectus mortality, reduction in progeny emergence and P. vulgaris seed weight loss than the control. Terminalia catappa however, exhibited the best insecticidal potential. Terminalia catappa and Solanum melongena were very effective in inhibiting the reproduction and progeny emergence of A. obtectus, but increased adult mortality resulting in weight loss suggesting their potential in controlling A. obtectus on stored P. vulgaris. Original Research Article